This invention relates to a method and system for dynamic downlink power control in a time-division multiplex wireless system.
Presently, many time-division multiple-access (TDMA) wireless systems use no dynamic downlink power control based on the actual activity of mobile stations. Instead, the downlink transmit power is typically set at a fixed level high enough to provide an adequate downlink signal to the mobile station receiving the worst downlink signal strength on the carrier. For example, the mobile station receiving the worst downlink signal strength may be located furthest away from a base station site transmitting to this mobile station. Meanwhile, the base station may provide one or more closer mobile stations to the base station site a stronger signal strength than is really required to maintain reliable communications with the furthest mobile station. Accordingly, the difference between the power required by one or more closer mobile stations and the actual power received by the closer mobile stations is, in essence, wasted power that increases co-channel interference. Thus, a need exists for reducing interference and increasing wireless system capacity in a time-division multiplex system through an enhanced downlink power control scheme.
In accordance with one aspect of the invention, a method for controlling downlink power in a time-division multiplex wireless system may provide different downlink transmit signal powers to different time-division multiplex channels of a single carrier. A base station receives a measured signal parameter data for a downlink transmit signal of a time-division multiplex channel. The base station determines an initial adjustment for the downlink transmit signal power of the time division multiplex channel if the measured signal parameter data differs from a target signal parameter data. The base station determines a revised adjustment for the downlink transmit power of the time division multiplex channel based on the initial adjustment and at least one adjustment range as appropriate to achieve synchronization of the demodulation of the downlink transmit signal. The initial adjustment is based on dynamic measurements of signal parameter data, whereas the revised adjustment may be based on the capabilities of the mobile station or other considerations.